We propose to design and synthesize binuclear copper complexes composed of two Cu(I) atoms encompassed within a single hexadentate macrocyclic ligand as models for copper containing proteins. We will attempt to isolate and structurally characterize a stable dioxygen complex of Cu(I) with the oxygen molecule bound by two contiguous Cu(I) atoms. The non-free radical oxidation reactions of these complexes with biochemical substrates will be explored and the mechanism(s) of action studied in detail. Every attempt to isolate and fully characterize intermediates will be pursued. The behavior of these systems will be carefully compared to the biochemical action of the protein systems using such criteria as the "NIH Shift", stoichiometry, selectivity, etc. Thus the overall objectives of the proposed project are to elucidate the nature of the active site in copper transport and oxidase proteins and to develop practical oxidation catalysts based on Cu(I).